This is the same as a project previously entitled "Biochemical Composition of Photoreceptor, Neuronal and Glial Cells of Normal and Pathological Retina and Brain" (Z01 EY 00135-03 LVR). The broad aims of the project are to study the biochemical composition of retina, pigment epithelium and related structures of the eye in normal circumstances and in retinal and choroidal diseases of experimental or genetic origin. Topics of current interest are: (1) concentration and distribution of inorganic constituents in eye tissues (retinal rod outer segments, pigment epithelium, retina and aqueous humor) by flameless atomic absorption spectroscopy; major physiological cations, as well as silicon, trace metals and chloride are being studied; (b) ultrastructural localization and physiological function of calcium in pigment epithelium and retina; (c) possible involvement of calcium in retinal and choroidal diseases; and (d) study of hybrids of RCS and spontaneously hypertensive rats to determine whether the slow onset type of retinal degeneration seen in the latter is inherited at the rod or another gene locus or is due to light damage in an albino animal.